Aptamers and Quantum Dot-Based Assays

Qnantnm dots (QDs) are nearly spherical flnorescent nanocrystals composed of semicondnctor materials that bridge the gap between individual atoms and bulk semiconductor sohds. Owing to the quantum-size effect, they exhibit size-tunable bandgaps and luminescence energies. They can be fabricated in a variety of materials, such as small regions of one material being buried in another material 

APTAMER-BASED BIOANALYTICAL ASSAYS AMPLIFICATION STRATEGIES 

Similar to DNA-based applications, QDs have been conpled to aptamers for the recognition of proteins (Levy et al., 2005 Choi et al., 2006 Hansen et al., 2006 Ikanovic et al., 2007). Most of these very recent applications rely on optical detection, whereas in only a very few cases (Hansen et al., 2006) an electrochemical transdnction have been employed. 

An innovative detection scheme, still based on optical transduction with QDs and aptamers, was presented by Choi et al. (2006). The authors discovered that PbS QDs could be passivated by a DNA aptamer becoming water soluble and 

These examples of the coupling of aptamers with the coding and amplification characteristics of QDs demonstrate the high potentialities of these methods, with particular attention to the simultaneous detection of different proteins or the detection of barely optically measurable molecules such as bacteria. 

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